1. Field of the Invention
The present invention relates in general to the close protection of a work station situated in a contaminated atmosphere, and more particularly to a device for the close protection of products which are sensitive to contamination by contaminating agents conveyed by the ambient environment, said products being positioned on a worktop such as a conveyor.
2. Description of the Invention
The ends of a conventional protection device for protecting products that are sensitive to contamination are generally closed by leaktight walls, and the air gap created between the wall and the adjoining end of the device constitutes a risk zone where inductions of contaminated ambient air may occur. The induction of contaminated ambient air produced by suction, consists of a flow of contaminated air directed toward the worktop where the sensitive products are arranged. This contaminated air flow then mixes with the sterile air stream diffused by the protection device and pollutes it.
The invention finds a particularly advantageous application in the field of the agro-foodstuff or pharmaceutical industry where the products are generally sensitive to the contamination conveyed by the ambient environment during their manufacture, and while they are being transported on a conveyor prior to their packaging.
Such a device according to the invention makes it possible in particular to protect an individual worktop for manufacturing and/or transporting sensitive products such as these, such as a conveyor on which said products are positioned, by diffusing a stream of sterile air in a direction substantially perpendicular or parallel to said conveyor, said device extending along said conveyor.
In certain cases, it may happen that the aforesaid device for close protection has at least one end adjoining a wall so that there is an air gap between said wall and said end.
This wall is for example an outlet wall of a machine such as an oven, rising vertically and having an aperture opening onto said worktop protected by the protection device.
This wall can also be an end wall of another similar device for close protection, abutted with said protection device without mechanical fixing, so as to constitute therewith an assembly for the close protection of a worktop of large length.
To alleviate the drawback of conventional protection devices discussed previously, the present invention proposes a novel device for the close protection of products arranged on a worktop such as a conveyor, which are sensitive to contamination from the ambient environment, by diffusion of a sterile air stream in a direction substantially perpendicular or parallel to said worktop, said device extending along said worktop and having at least one end adjoining a wall so that there is an air gap between said end and said wall, characterized in that said end is formed by a porous wall made of a perforated material, extending substantially perpendicularly to the longitudinal axis of said device, in such a way as to create in said gap a sterile air leakage directed outward away from the worktop, this sterile air leakage countering any ambient air induction into said gap toward said worktop.
According to other advantageous and nonlimiting characteristics of the invention:
a) the device comprises a sheath made of a flexible material diffusing a sterile air stream in a vertical direction substantially perpendicular to said worktop, said sheath being formed of a quasi-leaktight upper wall and of a porous lower wall made of a perforated flexible material, extending longitudinally along the axis of the sheath and delimiting between them a sterile air supply duct, and said end of the sheath being formed by a porous wall made of a perforated flexible material;
b) said end wall and the porous lower longitudinal wall of the sheath are made from a material of like porosity;
c) the perforated flexible material constituting the porous lower longitudinal wall and said end wall of the sheath is a synthetic fabric such as a polypropylene or polyester fabric;
d) each longitudinal edge of the upper longitudinal wall of said sheath is continued by a skirt which extends vertically toward the worktop and which constitutes a means of diffusion of sterile air at high velocity relative to the porous lower longitudinal wall of the sheath which diffuses the sterile air at low velocity;
e) the device comprises a plurality of sheaths made of a flexible material, juxtaposed so that their axes are parallel and arranged in one and the same plane parallel to the worktop, said sheaths covering the entire width of said worktop. According to a preferred variant of this device the external longitudinal edge of the quasi-leaktight upper wall of the sheath situated at each end of the juxtaposition of sheaths, is continued by a skirt which extends vertically toward the worktop and which constitutes a means of diffusion of sterile air at high velocity relative to the porous lower walls;
f) the two skirts of the sheath or of the juxtaposition of sheaths are of the same length and extend up to the immediate proximity of the worktop;
g) the two skirts of the sheath or of the juxtaposition of sheaths have different lengths, a long skirt whose length is approximately equal to the height allowed for between the axis of the sheath and the worktop and a short skirt whose length is approximately equal to half the length of the long skirt;
h) the device comprises at least one ventilation nozzle arranged on a longitudinal edge of said worktop and able to produce directed toward said products a sterile air stream in a horizontal general direction substantially parallel to said worktop, said ventilation nozzle comprising at its outlet an air diffuser made of a perforated material provided with upper and lower parts which produce an anti-inductive air flow whose velocity of diffusion exhibits a component normal to the worktop, said end of said ventilation nozzle being formed by a wall made of a perforated material;
i) said end wall of the ventilation nozzle and the upper part and lower part of the air diffuser are made from perforated sheet of like porosity;
j) the ventilation nozzle comprises at the level of said porous end, on its upper surface extending horizontally up to its outlet, a strip of perforated material forming a sterile air flow directed essentially vertically away from the worktop;
k) the device consists of a cubicle positioned above the worktop, supplied with sterile air and having a porous lower wall for diffusing sterile air in a vertical direction substantially perpendicular to the worktop, said porous wall being made of perforated sheet and exhibiting a profile such that it ensures central diffusion of sterile air at low velocity bordered on each side by a diffusion of sterile air at high velocity, said end of the cubicle being formed by a wall comprising at least one porous zone made of a perforated material extending over the entire width of said cubicle and rising from the lower edge of said cubicle to a certain determined height.
The invention also proposes an assembly for the close protection of products arranged on a worktop such as a conveyor, which are sensitive to the contamination conveyed by the ambient environment, characterized in that it comprises a device according to the invention as defined in characteristics a) to f) and at the extremity of said device, at least one ventilation nozzle arranged on a longitudinal edge of said worktop, able to produce directed toward said products a sterile air stream in a horizontal general direction substantially parallel to said worktop, said ventilation nozzle comprising at its outlet an air diffuser made of perforated material comprising upper and lower parts which produce an anti-inductive air flow whose velocity of diffusion exhibits a component normal to the worktop, said device furthermore comprising at the junction with said ventilation nozzle a vertical end skirt extending in a plane perpendicular to the planes of the lateral skirts of said sheath, directed toward said worktop up to a determined distance therefrom so as to permit the passage of said products under said end skirt.
It further proposes an assembly for the close protection of products arranged on a worktop such as a conveyor, which are sensitive to the contamination conveyed by the ambient environment, characterized in that it comprises a device according to the invention as defined in characteristics a) to e) and g) and at the extremity of said device, at least one ventilation nozzle arranged on a longitudinal edge of said worktop, able to produce directed toward said products a sterile air stream in a horizontal general direction substantially parallel to said worktop, said ventilation nozzle comprising at its outlet an air diffuser made of perforated material comprising upper and lower parts which produce an anti-inductive air flow whose velocity of diffusion exhibits a component normal to the worktop, said device furthermore comprising at the junction with said ventilation nozzle a vertical end skirt extending in a plane perpendicular to the planes of the lateral skirts of said sheath, directed toward said worktop up to a determined distance therefrom so as to permit the passage of said products under said end skirt.